New achievements hint at reverse Dragonriding races in Patch 10.0.5.
In the first dataminable Patch 10.0.5 build, Blizzard added new achievements for reverse Dragonriding races, which require players to complete the existing courses in reverse.
You can also earn new customization options for your Dragonriding drakes when you complete all the reverse races in a zone. Some examples:
Azure Span Reverse: Silver
Obtain silver in all reverse races in Azure Span.
Drake Customization: Highland Drake – Brown Hair
Thaldraszus Reverse: Silver
Obtain silver in all reverse races in Thaldraszus.
Drake Customization: Cliffside Wylderdrake – Blonde Hair